Free University of Berlin

No, you are not eligible because it's required Bachelor's degree in economics or law.

No the Master of Science in Management and Marketing course thought in English in University of Berlin but its not free.

Yes, Delhi University teaches BBA courses in English.

These are the admission requirements:
International students seeking admission to a Master's Degree or double degree programme need to submit the following documents:
Signed online application form via university-assist that you would get after completion of the online application. University degree certificate that includes subjects, grades and credit points and international degree certificate with translations. International students need to submit proof of their English proficiency if their mother tongue is not English. Motivation letter and a portfolio. So there are no entrance exams.

It's not quite possible for you to get admission in NIT Warangal, but you can get admission in other NITs like NIT AP, NIT Puducherry.
To know which all NITs you are eligible to apply, use the college predictor tool:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

Hi,
A good MBA programme requires an applicant to hold a Bachelor's degree, work experience of at least 2-3 years and a GMAT score. You have to check university websites for university specific requirements. There could be MBA without work experience in Germany or look for MS Management. MBA programs are expensive. It could be in the range of INR 8 to INR 30 Lacs.